MPEG Media Transport (MMT) is a new media transport standard technology developed by ISO/IEC WG11 (MPEG) system sub-working group in 2010.
In the existing MPEG-2 system, an MPEG-2 transport stream (TS) technology has been standardized for packetization, synchronization, and multiplexing for audio/video (AV) content transmission and now is widely used. However, in a packet transmission environment in which a network is based on an Internet protocol (IP), the MPEG-2 TS is inefficient.
Thus, ISO/IEC WG 11 MPEG has recognized the need for a new media transport standard and started MMT standardization, in consideration of a new media transport environment and a media transport environment expected in the future.
In an MMT payload header that is currently considered by the MPEG system sub-working group, an MPU sequence number (hereinafter referred to as an “MPU_sequence_number”), which represents a sequence number of a Media Processing Unit (MPU), is included in a data unit (DU) header.
In the case where a plurality of data units (DU) are aggregated in one payload, the number of DU headers included in the payload header corresponds to the number of aggregated DUs. If the aggregated DUs are media fragment units (MFUs), these MFUs are fragments extracted from a same MPU, and thus have a same MPU_sequence_number.
Accordingly, in the case where a plurality of MFU DUs are aggregated in one payload, each of the MFU DU headers includes a same MPU_sequence_number, in which the same MPU_sequence_number is repeated unnecessarily in an MMT payload header for a number of times corresponding to the number of MFU data units.
Meanwhile, the MMT payload header of current MMT standard does not include an MFU sequence number (hereinafter referred to as an “MFU_sequence_number”), which represents a sequence number of MFU included in an MPU. The MFU_sequence_number is important information that indicates sequential relations between MFUs in an MPU. Thus the MFU_sequence_number can be used for both a receiving entity and a sending entity to identify a sequence number of an MFU lost in a transmission process in the case where a discontinuous increase of MFU sequence number values occurs. Accordingly, MFU sequence number information is required to be included at an appropriate position in an MMT payload header.